A metal of which the surface is finished as a mirror surface, an interface generated by voids or the like, and a polymer membrane or the like using a laminated structure of a transparent dielectric for reflection has been known as a reflective material of a reflector for lighting. The polymer membrane has a small influence of degradation due to temperature and humidity or the like, and a reflective material having lightweight and good reflective efficiency can be obtained. Furthermore, since the polymer membrane or the like using the interface generated by the voids has excellent characteristic such as easy supply of uniform light by using diffuse reflection, the polymer membrane has been positively used as a reflective material for lighting having a large area and the necessity of uniform shining such as a back light device for displaying information.
As a three-dimensional structure material using the conventional polymer membrane material, for example, the three-dimensional structure obtained by bonding the polymer membrane on an aluminum plate and bending the aluminum plate has been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 11-198284 (paragraphs [0022] to [0045]) as the reflector for lighting. The structure material is strong and can hold the shape firmly. However, when a product receives an external force during a processing process and transportation or the like, distortion tends to remain in the product shape, and it is difficult to exhibit an optical performance at the time of the design. In addition, it is also difficult to install the product on a frame. The weight is heavy, and it is difficult to realize a complicated shape which is formed by deeply bending and in which various shape is compounded.
For example, in Japanese Patent Application Laid-Open (JP-A) No. 2003-22701 (paragraphs [0012] to [0018]), one obtained by bending and processing a white polymer membrane having a thickness of about 1 mm has been disclosed. However, the structure material had problems that the raw material tends to be fractured when a bent part thereof is bent deeply or extended at the time of a processing process and installation, and stress distortion tends to remain in a film material, and thereby it is difficult to maintain highly precise shape.
It could therefore be helpful to provide a reflector for lighting which has shape holding property, flexibility and lightweight property.